Dr. David Furness, CC BY-NC 4.0
Every cell in your body has its own post office. At the Golgi apparatus, fresh-made proteins arrive, ready for shipment. As the proteins work their way through the stacks of flat, ribbon-like membrane (center), the Golgi apparatus sorts and modifies them one last time before shipping them off to their destination.
The proteins “shipped” in neurons include ion channels, receptors, and neurotransmitters. The Golgi apparatus packages neurotransmitters into small packets called vesicles. The vesicles dock at the end of axons, near the synapse, waiting to be released. When an electrical signal rushes down the axon, the increase of positive ions allows calcium into the neuron, triggering the release of the vesicles. The vesicles fuse with the cell membrane and dump their contents into the synapse. The neurotransmitters make their way across the synapse to bind with receptors on the post-synaptic neuron, further spreading the message or triggering long-term changes in gene expression. Shipments from the Golgi apparatus comprise each step of this cell-to-cell communication: the ion channels that let calcium inside, the neurotransmitters flooding the synapse, and the receptors waiting on the other side.
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